One passenger drowned and four others remain missing after their boat hit a submerged tree stump and capsized on Sirikit reservoir in Tha Pla district of Thailand’s northern province of Uttradit.

Rescue workers managed to pull five other passengers and the boat’s skipper from the water, but 4 are missing and one body has since been recovered from the water.

The boat was leaving Ban Huay Ta village in Tha Pla district, carrying 10 passengers and a car, bound for Ban Tha Rua when it struck the stump as it approached the Koh Men and Koh Tao islets.

The director of Phrae provincial marine office said that the water level in the reservoir has dropped substantially and the boat skipper may have lost track of the navigational route, causing the vessel to hit the submerged obstacle.